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Histology-Pathology > Fixation > Flashcards

Fixation Flashcards

1
Q

Primary Objective of Fixation

A

To stabilize proteins which would preserve tissues and cellular components in a life-like state that would present autolysis and putrefication.

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2
Q

Classification according to Action

A

Microanatomical
Cytological
Histochemical

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3
Q

Permit the GENERAL microscopic
study of the structures without altering the
structural pattern and normal intercellular
relationship of the tissues in question.

A

Microanatomical Fixatives

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4
Q

Preserves the specific parts and
particular microscopic elements of the cell
itself

A

Cytological Fixative

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5
Q

Characteristics of a “ideal” fixative

A
  1. Cheap
  2. Stable
  3. Safe to handle
  4. Must only produce minimum shrinkage and distortion of cell components
  5. Hardens tissue
    .6. Isotonic for minimal physical and chemical
    alteration of the cells.
  6. Permit the application of many staining procedures
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6
Q

True or False. It should have at least ONE

characteristic to be considered a “good” fixative

A

False. Fixative should have at least TWO or MORE of the characteristics to be considered a “good” fixative.

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7
Q

From oxidation of methyl alcohol

A

Formalin

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8
Q

Pure Stock Solution - Highest concentration of Formalin equal to 100%

A

37-40% Formalin

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9
Q

Usual dilution of Formalin or % solution.

A

10% Formalin solution

Dilution: 1:10 or 1:20

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10
Q

Formalin Pigments are formed from?

A

Acidic formalin solutions due to formation of formic acid by oxidation of formalin.

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11
Q

Removing Formalin Pigment

A

Kardasewitsch Method
Lillie’s Method
Picric Acid Method

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12
Q

Measurements by which Pathologists cuts small portion of the organ.

A

3-5 mm thickness

3 by 2.5 cm in area

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13
Q

A microanatomical fixative recommended for fixation of CNS and GENERAL post mortem
tissues and SILVER IMPREGNATION

A

10% Formol Saline

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14
Q

Considered as BEST GENERAL fixative and for tissues containing IRON GRANULES.

A

10% NBF

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15
Q

10% NBF are most recommended to used for?

A

preservation and storage of SURGICAL specimens
RESEARCH specimens
Tissues with IRON Granules
Elastic Fiber preservation

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16
Q

Advantages of 10% NBF?

A
  1. Doesn’t cause formalin pigment preventing precipitation of acid.
  2. Doesn’t require for post-treatment
  3. Fixative of choice in tissues containing Iron pigments.
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17
Q

Recommended for routine POST-MORTEM tissues

A

Formol Corrosive/Sublimate

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18
Q

Satisfactory for EM

A

Glutaraldehyde

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19
Q

Most common metallic fixative

A

Mercuric Chloride

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20
Q

Advantages of Metallic Fixative

A
  1. Increase staining Brightness
  2. Nuclear Detail
  3. Applied for Hematopoietic reticuloendothelial tissues.
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21
Q

Recommended for TRICHROME staining and GAA is added before use.

A

Zenker’s Fluid

22
Q

Heidenhain’s Susa

A

SKIN TISSUE BIOPSIES

23
Q

Chromate Fixatives

A

ROCK

Regaud’s (Moller’s): Chromatin, Golgi bodies, Colloid containing tissue
Orth’s: Rickettsia & Early Tissue Necrosis
Chromic Acid: Carbohydrates
K2CrO4: MITCHONDRIA

24
Q

Recommended for ACID MUCOPOLYSACCHARIDE & CT Mucin

A

Lead Fixative

25
Q

Best for GLYCOGEN demonstration & allows brilliant staining with the TRICHROME METHOD

A

Picric acid

26
Q

Picric acid fixative for EMBRYOS

A

Bouin’s Solution

27
Q

A NUCLEAR fixative used to form COMPOUND soln. that fixes and precipitates NUCLEOPROTEINS (Chromosome & Chromatin)

A

Glacial Acetic Acid

28
Q

Methanol

A

BM and Blood Smears

29
Q

Isopropanol

A

Touch Preparations

30
Q

Gendre’s Fixative (Alcoholoc Formalin)

A

SPUTUM that coagulates mucus

31
Q

Fixes conjugated FATS and LIPIDS permanently

A

Osmic Acid/Osmium Tetropxide

32
Q

Differentiate Flemming’s Solution wit GAA and without GAA

A

Flemming’s with GGA: NUCLEAR preparation and PERMANENTLY fixes fat

Flemming’s without GAA: CYTOPLASMIC structure (mitochondria)

33
Q

Heat Fixation

A

Used:
Frozen Tissue Sections
Bacteriologic Smears

34
Q

Fixing brain tissues for diagnosis of RABIES.

A

Acetone

35
Q

This process removes excess Fixatives.

A

Washing Out

36
Q

Enumerate what are removed by the ff. solutions in washing out.

  1. Tap Water
  2. 50-70% Alcohol
  3. Alcoholic Iodine
A 
1. Tap Water - excess chromates, 
formalin, osmic acid (NOT Bouin’s)
2. 50-70% Alcohol - excess picric acid 
 (Bouin’s)
3. Alcoholic Iodine - excess mercuric 
fixatives
37
Q

True or False. Formalin Penetration is 1mm/minute

A

False.

Formalin penetration - 1 mm/hr

38
Q

True or False. Specimen should be transferred > 1 hour to fixative quickly.

A

False. < 1 hour.

39
Q

Volume of Fixing fluid-to-Tissue

A

15-20: 1

40
Q

A secondary fixation

A

Post-chromatizarion

41
Q

Fixation time

A

6-24 hours

42
Q

Histopathologic Techniques

A
  1. Fixation
  2. Decalcification
  3. Dehydration
  4. De-alcoholization or Clearing
  5. Infiltration or Impregnation
  6. Embedding
  7. Trimming
  8. Sectioning
  9. Staining
  10. Mounting
  11. Labelling
43
Q

Factors involved in Fixation

pH:
Thickness: EM - \_\_\_\_; LM - \_\_\_\_\_\_\_
Temperature: 
 Traditionally @ RT - \_\_\_\_\_\_\_\_\_\_\_
 For tissues w/ TB - \_\_\_\_\_\_\_\_\_\_\_\_
Osmolality: 
 Slightly Hypertonic - \_\_\_\_\_\_\_\_\_\_
 Isotonic - \_\_\_\_\_\_\_\_\_\_\_\_
A

Factors involved in Fixation

pH: 6-8
Thickness: EM - 1-2 mm; LM - 2 cm
Temperature: 
 Traditionally @ RT - surgical specimens
 For tissues w/ TB - Formalin @ 100C
Osmolality: 
 Slightly Hypertonic - 400-450 mOSm
 Isotonic - 340 mOsm
44
Q

Formula: 10% NBF

A

Monosodium phosphate
Disodium phosphate
40% Formalin

45
Q

Formula: Zenkers Fluid

A

Mercuric Chloride
Potassium Dichromate
GAAA

46
Q

Formula: Helly’s - Zenker’s Formol

A

Mercuric Chloride
Potassium Dichromate
Sodium Sulfate
40% Formaldehyde

47
Q

Formula: Heidenhains

A 
Mercuric Chloride
NaCl
Trichloroacetic Acid
GAA
Formaldehyde - 40%
48
Q

Recommended for demonstration of Ricketssia

A

Orth’s fluid

49
Q

GAA solidifies at ____

A

17C

50
Q

Precipitates proteins

A

TCA

51
Q

Acetone fixative is used at ice cold temperature ranging from ____ to ____

A

-5C - 4C

52
Q

Secondary fixative in Post chromatization

A

2.5-3% Potassium dichromate

Histology-Pathology (5 decks)

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